Functional outcomes after ischemic stroke improved over recent decades, while no significant change has been observed in patients with hemorrhagic stroke, according to study results published in JAMA Neurology.

Long-term changes in age at onset, incidence, and mortality of stroke have been seen in several populations. For example, in the past half century, the age-adjusted incidence and mortality of stroke has decreased in Japan, according to the researchers. However, there has been a slow down over recent decades. Researchers believe recent changes in demographic characteristics and therapeutic technologies may play a role in neurologic severity and functional outcomes of patients with stroke.

The objective of the current study was to determine the impact of changes in demographic characteristics and therapeutic technologies on stroke severity and functional outcomes of patients with acute stroke by sex.

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The researchers used the Japan Stroke Data Bank, a 20-year-long nationwide hospital-based registry of hospitalized patients with acute stroke or transient ischemic attack from 130 academic or regional stroke centers throughout Japan from January 2000 through December 2019. A total of 135,266 patients (39.8% women; median age, 74 years) with ischemic stroke, 36,014 patients (42.7% women; median age, 70 years) with intracerebral hemorrhage, and 11,800 patients (67.2% women; median age, 64 years) with subarachnoid hemorrhage, were identified.

The National Institutes of Health Stroke Scale was used to assess initial severity of ischemic stroke or intracerebral hemorrhage, and the World Federation of Neurological Surgeons was used to assess the severity of subarachnoid hemorrhage. Functional outcomes were determined using the modified Rankin Scale (mRS) score.

Across all 3 stroke types, initial stroke severity, as determined by the National Institutes of Health Stroke Scale or the World Federation of Neurological Surgeons scores decreased throughout the 20-year period. Furthermore, medians ages at onset increased, and unfavorable outcomes (mRS of 5 to 6) and in-hospital deaths decreased in both men and women.

For patients with ischemic stroke, favorable outcomes increased over time after age adjustment but then stagnated, or even decreased in men. However, following multivariable adjustment, including reperfusion therapy, the functional outcome improvement was no longer significant.

For patients with intracerebral hemorrhage favorable outcomes (mRS of 0 to 2) decreased over time in both men and women, but unfavorable outcomes and deaths decreased only in women. For patients with subarachnoid hemorrhage, no change in the proportion of patients with favorable outcomes was reported, while rate of unfavorable outcomes and deaths decreased in both men and women.

The study had several limitations, including potential bias as high-volume stroke centers tended to join the study and the findings may not be generalizable to low-volume hospitals, exclusion of more than 6000 patients due to unavailable data on stroke types or demography, no long-term outcomes, and no available data on the effect of the COVID-19 pandemic on the outcomes.

“[S]troke became milder in severity during the past 20 years regardless of sex or stroke types although age at stroke onset became older in the nationwide stroke registry in Japan. Short-term functional outcomes at hospital discharge improved gradually in patients with IS [ischemic stroke], presumably partly owing to development of acute reperfusion therapy. In contrast, outcomes of patients with hemorrhagic stroke did not clearly improve during the same period,” concluded the researchers.

Disclosure: Some study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of authors’ disclosures. 


Toyoda K, Yoshimura S, Nakai M, et al. Twenty-year change in severity and outcome of ischemic and hemorrhagic strokes. JAMA Neurol. Published online, December 6, 2021. doi: 10.1001/jamaneurol.2021.4346